How to adjust camera clipping for object?
this is a good question.  the shiftX value will shift the camera however many units in the X direction, but the point of origin will stay stationary, if that makes sense.  The camera has a point of origin, like every object. And also like every object, it will rotate around it's point of origin.  In this case, the point of origin is the tip of the camera where all the lines meet (See picture)  
The origin can be seen as a small orange dot.  If you wish to change the origin, there are a number of ways to do this.  You can see all the options by going to: Object-Set Origin; and then choose your preferred position.  Hope I answered your questions correctly!